(1) Field of the Invention
The present invention relates generally to systems for handling fabric pieces for apparel manufacture and, in particular, to a new and novel pickup device for such a system.
(2) Description of the Prior Art
The move towards automation in the apparel industry has been hindered by the lack of a commercially viable means for removing pieces of fabric, one at a time, from a supported stack of fabric pieces. In order for the pickup device to be practical, it must have a high degree of reliability in separating a single piece of fabric from the top of a stack without picking up two or more pieces and, in addition, must be economical to manufacture and operate. For example, it has been estimated that one malfunction in one thousand operation cycles is the degree of reliability necessary for a profitable manufacturing operation.
One approach to this problem is illustrated in the Stone et al. patent (U.S. Pat. No. 3,558,091) which discloses an apparatus and method for picking up individual pieces of cloth from a stack, carrying the individual pieces of cloth away from the point of picking them up, and depositing them individually on a support, such as a conveyor. The entire disclosure of this patent is hereby incorporated in the file of the present case by reference and in its entirety. The pickup head, as taught by Stone, has a sleeve having one end secured to the piston of an air cylinder and the lower end formed to provide a plurality of equally spaced fingers having cloth-gripping or pinching bottom terminals. The sleeve is surrounded by a head or housing having a bore for receiving the sleeve which includes a lower adjustable portion which has a bore which engages the finger terminals when the air cylinder is actuated. Consequently, when the air cylinder is displaced downwardly, the surfaces of the gripping fingers contact the surface of the lower housing which results in closing the fingers so as to pinch a layer of cloth preparatory to lifting the cloth from the stack.
The Tex-Matic product brochure shows a fabric pickup having six individual gripping fingers equally spaced apart from one another. The fabric pickup device as disclosed by the Tex-Matic product brochure is air operated by a single cylinder which actuates the plurality of pickup fingers simultaneously. However, the product brochure does not describe the details of its operation or show a cutaway of the device.
In addition to the above "clutch-type" devices, various other pickup devices employing gripping jaws or wires or both have been proposed. U.S. Pat. Nos. 4,444,384; 4,526,363; and 4,697,837 are illustrative of such approaches.
Certain disadvantages become apparent with such designs. First, most of the prior art pickup devices are designed in such a way that a compound movement in both the vertical as well as the horizontal planes must be made in order to contact and pickup the fabric piece. This requires that the position of the device be carefully controlled in both the x, y directions and the z direction.
For example, in the construction of the pickup device as taught by Stone, the pickup fingers themselves actually move and, consequently, the distance between a fabric piece and the pickup head varies when the device is actuated. As a result, such a device cannot be readily adapted to a more simple and reliable x, y coordinate control system.
Second, many of the prior art devices require or at least prefer that the surface of the cloth be penetrated in part by a wire or needle in order to increase the reliability of the cloth pickup. Such penetration can result in undesirable surface defects, particularly in tightly woven or shear fabrics.
Finally, prior art devices to date have been overly complicated and expensive to construct to such a degree that they have not been widely adapted by the apparel manufacturing community. For example, the pickup devices as taught by Stone are each individually actuated by a corresponding individual air cylinder.
It has thus become desirable to develop a fabric pickup device for a fabric handling system that will reliably pickup pieces of fabric from a supported stack of fabric one at a time without picking up two or more pieces. It has also become desirable to develop a pickup device which will not mar the surface of the fabric. Finally, it has become desirable to develop a fabric pickup device which is simple and economical to manufacture and operate, thereby facilitating the move towards automation in the apparel industry.